Method of cutting the teeth of gears



A ril 18, 1933. o. G. SIMMONS METHOD OF CUTTING THE TEETH OF GEARS Filed March 27, 1930 7 Sheets-Sheet l April 18, 1933. o. G. SIMMONS METHOD OF CUTTING THE TEETH OF GEARS Filed March 27,' 1930 7 Sheets-Sheet 2 INVENTOR April 18, 1933. o. G. SIMMONS 4, 7 METHOD OF CUTTING THE TEETH OF GEARS Filed March 27, 1950 '7 Sheets-Sheet 5 INVENTOR April 18, .1933. O SIMMQNS 1,904,956

METHOD OF CUTTING THE TEETH- OF GEARS Filed March 27, 1930 7 Sheets-Sheet 4 lNVENTOR April 18, 1933- o. G. SIMMONS 1,904,956

METHOD OF CUTTING THE TEETH OF GEARS Filed March 27 1950 7 Sheets-Sheet 5 INVENTOR April 18, 1933. o. G. SIMMONS METHOD OF CUTTING THE TEETH OF GEARS Filed March 27, 1930 7 Sheets-Sheet 5 .INVENTOR A ril 18, 1933. 0. ca. SIMMONS METHOD OF CUTTING THE TEETH OF GEARS Filed March 27, 1930 7 Sheets-Sheet 7 INVENTOR 7 the'cutting of helical gears, using the same helical gear shaped cutter and showing the positionni thecuttertin dotted lines at" the. beginning; ofijthe {cutting operation in mesh;

- with the rimaginaryfcurvilinear rack shown ferred to. 7 .vFig fiis, a View in i'this drawing a right hand; helical-gear theiielical angleoii the cutter.

" j '49:. -,My;ipresentinventionresides-in theflmove- Tmentsof a1 conimercia11y knownspiraL-cute tercontinuouslyrotating in one direction'and, v reciprocating acrossthe facei'ofthe gear 45' .blai1k:or;w0rk.; one stroke of whichv reciprorating 1 m? Q BI tgi-s in efiect; a cuttingstrokein jcutting contact with the work, while the cutting, it being areturn of the cutter. to

thecutting' strOkeL v s l a ge era n cr me p eviqe y ed ws he? was: see b a oved gr commbn iciirvilinear linetangent toethep-itchw circlesofthecutter andgblank to' cause on'eg or thell-otherltopass transversely across the face te arI ea b ai p lid l r ri by dot and dash line; said imaginary curvie linear rackalsc' meshing with the finish'ed I helical gear, andshowing also the position;

of'the cutter in 'mesh with "said'imaginary curvilinear rack after it-has'completed the 7 "cutting of the teeth of the. helical gear r-' I Y A -7 gear blanktogproduce 'tWistedQteet-h'ofthe imilar to Fig. 5, except shaped cutter-ifs used to generate the twisted 7 teethl-fofthe lefthandi gear illustrated having a: ;h eli 'r; angle-1corresponding to the helix a; 7

duced inlthegears in all,casesjare colljl gatef FignZ- isa viewsim llar to -Eig l except that-in this view .thevcu'rvilinear rack isre- )isiadjromfthebrder shown in Fig.1 1 The apparatus wfor practicing my; inven v ti'o'n'utilizesa twisted tooth or a helical gear. Sh pe cutti'i which he ethanewiste F oga g v nea'ngl f. he i-xgz theormal-pitch V being the determiningfactor to -its ut iliza% it 1 tionjforj; ,generatingthegteeth of gears-g 1 'lhe felcommercially z known spiral cutter, E ,l}hlff01,; of a given norma1;.pitch mayabe used jto' cut the zteethxofany helicalor spur" g gear offthe given pitch." The normal pitch' "of; the cutter is, therefore, the determining a factorinthe practice ofjthis inventiOniii'the utilization of a given pitchcutter and not;

7 tion so. that thelplan practice of methodthat thefstraightjteeth' ,the same nature :asfg-l the combinedgan'gle produced;dependentmpon other: stroke fis non-effective, thatjisginofn- "curvilinear:movement' f,

the original position. This reciprocation of. t the cutter is maintained at a relatively rapidrate fof speed." At the, beginning of the Ireturnfstr'oke the cutter-is-preferahly given: an additional movementtowithdraw it from] contact gwith the gearg blank. i-At the; end; of the. return istr'oke; and at the beginning of h sfi i wtting ro t e mtt i ga n movements of" 83413115 as heretofore; described hereinafter; From-the, foregoin in1-generating'the-teetl ofanyfispur'orhelic ntopOsi'tiQn' toefiejct'cutting contact-j I left hand helicoid-tee; W V the work cwith thegsam'e cutte c p eeat ne me emen which has been given thelcurvilinear move- 7 ment referred to, which movement results inthe cutter and gear blank approachingeach 7 other. This curvilinear movement is continued in the same direction to move saidcutter and blank apart, the workmeanwhile rotating on an axis disposed to the. axis of the cutter .l e' reslponding h e iic ah the teeth of the cutter to producestr'aight 7 5 teeth the-'gearblank in one aspect of my; invention andin-fanother aspecto'f'my inven- 7 tion the axis of: .the cutter will be disposed f V to the axis of the' gear blank corresponding to; the s um}; of the measure of the; combined 1 helik"anglesfo'fthe'cutter and rhe helical 30 to the, imaginary curv mean crack :conj ugate 7 to the cuttert a From the oregolng i s 'unde tcoem e f a sipurfgearwilhresult ff thetflxS Of th W' rl pindle nd cu tenslpindle readjusted v i A and secured in angularpositio 0 ,orresp0nd1ng t, th chtl' helicoid teethgoir' the; iciltter twisted: teethpi the helical;

he w th the I f e the aforesaid'faxesl a1, adjusted andse cured at K 7 the cuftterr andggear andthati a helical gear of ean oppositei i fii. to that oi the twisted ,teethlof-a thegjcutt. wi f es lt i-feth new i s ed toa=10 eh willhe parallel,

othe-flothere 1 v,

I ya-rre en :m t. the subj ect' matter 20f ;th

I -a is, straight tee'th ina spiny; gear iiihfGghGliQflllJ teeth in a jspirallortwisted tooth gearjvill be v r i "the: adjust en't of; the axes 10 themwcrk end .ieutter. if Th the'imaginai'y rack;-

-' n rme i g wit .t eit'eth'nfither orkeandiz 1 the "teeth of'the cutter, resultingin rotary:-

and aswill hemore: particularlyqset f stood;thatinthexpt i i 0d a given :helicalcutt gear. and; in {the caselof t the; flatterright; or

m er O di istm ntief cutter an d work and the}' correl ation of curvilinea and, rota 5 rack is relatively; sl o f; the cutter'ande Y ice,"

the work and. the cutter,- the rotary move ments of the cutter and work will" be correlated with respect to each other and the rack, and therefore be relatively slower than the reciprocating movement of the cutte-r across the face of the work.

It is also of importance to know that the 3 cutter and work theaxis b'b ofthe cutter-4,

curvilinear -movemen-t of the cutter across the face of-thework is relatively slewer than the speed of. the reciprocatory rotary-movement of the cutter. r r

,Beferringto Fig. L the spur gear 1 is prouidedwith the straight tooth 2-and is adapted totrotate slowly on its axis. C in the direction of the arrow 3. The teeth 2 of the gear 1 are shown the drawings as having been cut completely by means of'the helical or twisted tooth gear shaped cutter 4, which is provided with the teeth 5.

The cutter 4: is adapted to be secured to the cutter spindle of suitable apparatus or machine'and to be continuously rotated in the direction ofthe' arrow 6 and simultaneously moved, slowly in the direction indicated by thearrowZ along a curvilinear line parallel to the curvilinear line-of movement .ofthe continuously moving imaginary curvilinear raekS, said imaginary curvilinear rack moving con-tlnuously 1n the curvilmear' direction indicatedby the arrow 9.

The. cutter 4 is known commercially as a 35 spiral gear shapercutter- 7 The position of the cutter 4: as shown in-the drawings, Fig. 1, is substantially the position ofthe cutter after it has-completed the cutting of the teeth 2 of the gear 1.

I :In this method thefirst position of the cutter 4, before cutting the teeth 2 of the gear 1,.isindicated'by'the same reference numerals with the capital letter A affixed. The cutter inthis position is shown by dotted lines and is assumed to be reciprocating toward and away from the observer along a line perpendicular to the plane of the sheet of drawings, Fig. 1, which is along line aa shown in Fig;

; 2 a required measure of distance to clear the gear 1, as illustrated in Fig. 2.

The gear shaper cutter 4A is alsorotating in the direction of the arrow 6A andmoving in the direction indicated by the arrow 7.

The rotary movement 3. of the; gear 1 and.

the rotary movement 6A ofthe gear shaper cutterdA is of such velocity as would be obtained if the gear 1 and the cutter 4A were meshing as shown; with the imaginary curvilinear rack 8, while the curvilinear rack 8 is continuously moving in the direction indicated by the numeral 9; meanwhile the cutter Li-rotating continuously in the direction of the arrow 6A also slowly moves along a curvilinear line in the direction of theiarrow-Z;

from the position ofthe cutter tothe, posinite length andits movement in thedirection of the arrow 9 is. continuous.

In the aforesaid rotary movements of. the

see Fig, 2, is disposed angularlywith respect; to the axis 0 c of the work. 1 to efiiect alignment between the teeth of the cutter in cut.- ting contact and the teeth of the work being operated upon by the said cutter.

It is further to beobserved that the. aforesaid reciprocating movement of the cutterfl. along the l ne a a, see Figs. 2 and 3-, 1s along a line parallel to the straight teeth of the spur gear illustrated and which is also along a. line. parallel to the axis 0-0 of said gear.

It is further obvious in the practice ofthe method referred to that the line 057 a is; the

path of reciprocating movement of the cut? ter and is to one side of the gear being cut when it is at the beginning ofthe operation ofjcutting the teeth 2 of the gear, and that it is at; the other side of the gear be-Ingcut when it is at thelend offthe' operation of cutting the teeth, see Figs. 2-and 3. 7

It will be understood that; I could just as:

readily continuously rotate and move the gear 1 in mesh with thiscontinuously mov-" ing imaginary curvilinear rack. across. and into and out of contact withthe reciprocat ing cutterv as I have moved thecutter in mesh with the rackinto and out of-contact with the gear as described. This is illustrated in the drawings,.Fig. 4-, the gear,eut-

ter and characters being indicated by the same reference numerals but having the capital letter B afiixed. V V

The presentinvention also provides a method of cutting helical gears of any desired helix angle with the same helical gearshaper cutter.

This is possible for the-reasonthat regardless of the angular position of the cutter axis. with respect to the axis. of the gear! blank, the cutter will generate a gear conjugate to itscurvilinear "rack, the teeth :of

which will mesh withanv gear of the same or an identical cutter. This isillustrated in i Fig. 5. the gear. cutter and charactersbeing ndicated by the same reference numerals but having the capital letter C aflixed.

It is'also obvious that I can by the method herein described, dispose the axes of the cutter and blank to such angular'positionsmne', with the other, and produce the spiral twisted teeth of left hand helical gears, using a right hand cutter. This is illustratedin Fig. 6, the gear, cutter and characters being.

indicated by the same reference numerals but having the capital letter D allixedp 3? with the'other.

. can

as: a

It will befurther observed in Fig.1 that gear a'nd cutter are disposed to each other at 1 angles determined by the angle of helix of the V i The straight teethofpjthe spurgear:illus trated in Fig. l'willresult if thegaxesof the workspindle and cutter'spindl'e are adjusted to andsecured in angular positions, one

' By thefexpresslo'n secured in angular position, withre'ference to Fig, l, I mean that" t the axis of the ork may be adjustably po-' sitioned perpendicular to the plane'of the m surface of the sheetof drawing of Fig.1, j when 'the axis of the cutter is adjustably dis-"v I posefdat an angle thereto, and vice versa.

The samemovements, however, as herein referred to will jcontlnueand points on the 7 m axis ofone will approach points on the axis of the otheruntil'finally the minimum measure of d stancebetween sa d axes 1s reached, the movements continuing as describedjwill increase the measure of d1s-' tance-between ,said points onthe aXes. In this movement, the axes of the work spindle and the cutterspindle; will alwaysbe disposed at an'angle to each other as illustrated 'infthe drawings, and the reciprocation of 25 the cutter will always be along a line per- 7 pendicular to the planenormal to the tooth helicoid, or,'.as illustrated in the'drawings,

along a line perpendicular to the plane of the sheet :of drawings, Figs. 1,14 5, and "6 The position of the cutter 4: as 1t begins to cut the teeth of the gear 1 is illustrated in 1 Fig. 2. It will be observed that the position of ,the 'c utter 4 is shown, for 'thef'p'urpose of illustration only, to the left of the gear '1 and of'its stroke it is'shown in dotted lines.

. as having been completed by the cutter 4-.

position of the gear 1 and cutter 4A. of Fig. 1,

andFig. 3 corresponds substantiallyto the position of the gear 1 and cutter 4i of'Fig, 1..

It i to be noted, with respect to Fig. 1,

duce the straight teeth of the spur gear shown.

axes of the cutter :and work'together with correct correlation of the moveni ents' hereinre- ,the a'x es of the work and cutter are disposed ter. v e With referenceto Iing used'ito out the teeth in the right hand helical gear, and furtherthat the axes of the gear plus theangle of helix of the cutter.

, p With reference to Fig. 6 it will be observed that in the case of a right hand helical cutter onits lowermostposition of the stroke, the cutter is 'shown l'n full llnes and at the top Thus Fig. 2 corresponds substantially to the that' a right hand helical cutter is used to proto' each other at the angle of helix in the cut- I v r g V y g wlth the blank While malntalnlng'm'termeshv Fig. 5 it willbe'observed that the same right hand helical cutter is beof the teeth of the cutter, the-axes of thework and cutter will be para'llel to' each other hand helical-gear of a .gi-ven hel-i xangle'isf cut by a right hand cutter of'a diflerenthelix-- From this, therefore, itfollows that if aleLft- ZP,

angle'theaxis of the work'and cutter w'il l be v disposed at an angle to each other equal to teeth of the cutter and the helix anglejofthe teeth to be generated in the 'gear blank-{The reciprocating movement of the cutter, however,'regardless of the adj ustment'of the axes thedifierence between; the helix angle of the 7 of the cutter and J work to-meet "conditions above referredto ,-will befalong a line parallel to the twisted teeth of the cutter and this line will be, as previously stated in-theexamplef referred to, perpendicular tothe sheets of" drawings of Figs. 1, 4, 5 and 6, or along the 3 lines a'a,Figs.I2'ar-1d 3. i

It is obvious that the relative-movements hereinbefore referred; to,'-with reference to the cutter, work and curviline ar rack 8,; of Flg. 1,- would result in the same ine-thodif the" 9 order of curvature of the curvilinear rack'was reversed from thatshown in Fig.1. This is illustrated in Fig. 7 in which the same-refer ence numerals are usedw'ith the' capital letter Eaffixed I r 7 Gears cut in accordance with the present 111 vention will roll on the curvilinear rack" cone;

jugate to the gear 'shaper cutter employed cal cutter conjugate tothe-same curvilinear rack will 'meshproperly with'each' other.-

It is to be understood thattheexpressions;

curvilinear rack, curvilinear racke'ofinfiin cutting them and allgears cutby the'helichordal tooth thickness.is'substantially equal to the tooth pitch line thickness WhatI claim'is: 1. The herein described method, of gen-v crating teeth, in. a gear blank-with a gear" shaper cutterghaving, helical teethtwhich comprises positioning thecutter with' its'axis 115 at an angle to theaxisof the'blank, rotating the cutterandblank in zinte'rmesh-ing relae of the blank and.simultaneouslymoving the cutter laterally into and out of engagement in g relation between the cutter and: blank. and an imag nary curvil near rack'conjugate to both the cutter and blankiand moving be .tion, reciprocatingthe cutter. across theface along a imes-tit the et t eml tena t wi h "r pe t t9 he b nk ttla a ommontwrt near l n tngent the p h-wh le re i hes" t t teni b ank etat tn the a; q t tt I 1 and blan at, t l a aetbt pe dvatwhich theyjtwpuldabeidriv n,

bxs ani-l mttgiaa yf; cur il n ar -11-a k1 n tw'i izz Ydistan t li e md; ipr ta ina G t Q entmte-th t eth fith f blank? 3 t hea-he e n desttib dvme hodi ofig etttttter a ng: hftl fl fi PFh w i r compri R ia illa the int ertw th; its xi at ana :tQ he t is of e lank: fe di t i -tit r; a gent ally w th; tits ol he blank Wh a to a n he; Qu terand -bl nkatsp e s su pl es-to maintain ,interineshing reatiqmwi h r-ep t to t ntma ina y; t

helicahteeth; which comprisesipositioning; the t cutter; with itsax isatan angle. to the axis} of a; itch-meshing; withgb'oth the cutterland ate the teeth ofthe gearblanka'n blank; reciprocating; the cutten-to genen '20 atingsa hz n ge tbltt k' w t ag ar ap r' t tter h i h l ltz et t hi co pr se Rositioningthe cutter with its aXiSata L-angle totthe axistd the blank rotating the cutter andz bla le a ifi rqnftf pe ipheral pee aea thtiwitahiml fimpa na t i e v inqn totbeg ar bl nkand tenat e sp d relationship with an imaginary curvilinear" rack an'd iwith a gear; shaper cutter having the llanki correspond ng t h x angle of th icutt nrte ht rot ting th c 'tt nd lankni n e m h na-re tien, r ip tin the} flutter at an: angle, to its axis across the fad l fzivthe blank nh i-di q o f; h ta s' Qia an n ttedingtzth rcu -t l e l y with respect to the: axis A of; theblank while maintaining intermeshing; relationship. be twe h u te t h nk a dath m gin y t 1 At me hod fi tnerati gr; th; a lan t tompr ing r ating 1 1 gear shap a t ,t ream Witha mat aear bl nk, ,rec p eating the cutter transversely o'f thewfaceof the geargblank,- ;-{and simultaneously moying the;;cutter and gearblank c l oser together by a relative movement along a curvilinear line i a 7 The method of tangent to a pitch circle of the cutter and gear blank. t

the axes of the cutter and gear blank being .disposed with respect to each other at an it? a -hi ar b ank wi h a g an s tapt t 4-The her,ein;;des cribed methodv of: g ne} along;.a-;eurvilinear line tan-genm to a; "pitch having helical teeth in jinternieshing erating helical, teethri'n a 1 gear; a blank:

generating helical teeth an le equal: o heti mi h lh l K-' 3ng 9i I thacutte andw thefhel xtangl a t Q-b ener tedz l blan i lp'se iz gth a ngt it lliv i ttrf in tangent fi i'i n Q reletofn hes cuttertaad a p ch-.201 th -8-,; l;hesn1ethod;ot gene atmg 1 y nvgeam anks w ic omp ise i otatlngia' "el atiYQit Qu innt start-shap du erha ing helicalitee hiot h as tme handis'as; the F teeth; t me; gener .Qdfl in. ha blank fin i' nt rmesh g 1.

rotating gflar blai1k,@1 h b ng d p stdia i nwa gl bl nkarr pondin-g o thee ng e vot het eeth SthQ ac ttenz ndg-tha hel,

angle ofz tet -l ebe ganerated i itheblan i I reciprooath-1g the acutte transyerselyioii h V newpelfpend llli f f c l ha ank al e to theplane normaLto tetooth helicoid, and v simultan us yv i a' th Quttemand; gear 7 lank. loser-Etogethen byji-relati e movement.

circle of: the cutter iandtia pitchi circle'ofthe gea a ka a; 1 T e e hodiofgene a ngh it l. eeth 4 t in gear blanks which comprises rotatingga ge sh pe tu t mhavingi a tee h intermeshing', relation with a? mati g; gear blank, the axes Ofwthfl cutter: and blank being arranged at an angle equal; 't'oithe-difi'erence between the helix; anglev' of the-teeth1013i ,htv t t er'a h l x-("angle p it e eethi oib gener o ies lank, rela iv yrreciproaati j ing th g n d ,bl nkttransv rs ly of th ir faces, and moving the 'cuttei'fand gear-blank lo er. bfYz ra Ye movement alo a currvilinear ine gento a pi ch i c eiaf heb terandagpitch circleo -t e=gear-blankg '1 The-metho to ige i t gh icahte 1) ng a l nk hi i mpi' s a atin I geart haped; cu t u y ng wh li i lt e th of,

th pp ieehand to theshejli igteethito be t et d Onz b n termeshingnelae ian w t a ro ng ge n b nka hei axessoi I 1 f, J tha uttert d ge rib a kf b ingm rranged ipar l lwt j h th rii 'r ativelyk iproeat: ngl h u e v nd blank't risverselytoftheir faces, and simultaneously nr ovingi theieutterj vandY-gear,blank closer; togethen'by a trelyatiwe it 1i.

movement along a curvilinear;linewtangent ma ia circle.ofithecutter-andtgean blank. t t t '11": The erei-ntdescribedtmethodpof 611:,

.l-ta-w gear sh pencutter wha g.:h lical;=teeth which ,j mpIi QQ-QPO it QniHgEthe cut er withzi siaxis atjani iangle to themxisqof, the blankf'correr, i

sp nding to t esum of:theihelix anglaof the teeth of he.v utteriamltthet elixdark 1 if I hsa eethv t ,1be.,'ge1l6r t dion hitblan tive ypmoying' he-cutter? c along f lcommonricmivi inea l heipith nircles gd iafih 2 he math mo a " recipt'ocatiiig the butter 'anctblanktfansizerse; 1y Oftheif faces I I 1 'ciir v iiiiiear "'TaCk'L'I'IiOYiIfgFvaldngf saidicurvi;

ii ieartangent line, and ffelatiiie'lyzreeipiecat I the cutter and-'bIank-traiisverse1 *lef their I eratmg helic l teeth in a gear blan gearsha per cutter having helical teethflwhieh] 1 par llel "to the; axis of r the; blank; relatively "ing the ciitter and 'blankiaterallyfelong pitehincles :oi; the; Gutters-and lilaiik min y fwdi ldfbe driveii by an imaginary f cie's to generate the" teethf the} gear blank.

. I The hl'il lfdesicribed' lnthdfdl 015;; genitii a;

co prises ositioning the butter with its xis 1 in r i 'aek moving ialO'iig Isa-id curvilinear I ange t ling-and ,ielati'vely ieeiprdating the a. ating helieal est-n ne ea blank'with' gear v enttenland' blank transversely efthei'n-faces idfg' ierate' theteethwf th geanblanigr i E 1E3? Theih'erein described inethod of genfe i-i shiperpiiiterghwing,heiicaiteetii wi iehgioi i the butter with its" axis' at a is. o-f"thehlan keetrespondf angle 'to the,

teeth ing to thestmi fthe heIiX angle f t-h' Qf the cutter and the helix angle of ieteeth 66 be genfatedin the blank} rotating the ci1t5 ten and blank at difierent peripheral speeds at theiij pitch 'ci'lttlesf imparting a relative inev mentte th ear blank and cutter at tli muvemene ogtii-egear blankandCuttei'nt the speeds ne'es'sariy' te maintain 'b'eth fin inte'r' ineshing relatidnshlp With an i aginary den;

7 tinuOiIsE mOw -ing curvilinear 'racki 'conjtigate t6 the guttenj and, gear, blank, and relatively J generate wif e?! 14, The-h'rein assent-ediii nibci oiggeiiei- 'atin-g'helicasl teeth in a; geaf blank 'withia' geai' allelf tof the axis of tlie-blaiikjrotating the cuft ti' and blank at :diifernt'jperiphen speeds] at thei r p'itc h blfCll-QSL imparting a relative speed emi sary: to maintain bet-h in" inter 11- meshing relationship With-"an iinaginaiyiebn-j; tinnenslylmelving clir vilinear' "rack con l gatie td the netterami gear lilank and relatively- ,ifeeipi'ocating ithe cutter and hlank-" ti ans I .versei i their-faces to? generate the'teeth 6f tli'gear"blank:'

= 151- The her;eiiide ribed: mailed-iii ener-i inteiiineshingrelationship;reciproeating"the cutteriaenbsstheiface'ot the blankands'imnl taneonsly annoying" i the 'cntte'f' laterally; intd d oul o .e g m fi /wi th b -nk w l .1 maintaining intei'm'eshing relaltion between- 1 blank and m'eving between the same 16." T lie hefein desc ibedmethod to the axis 6f the blank'e ii'espOndihg flfitlie I I he1iXangl e Of the Cutter teeth; rotating the" f Y c utter,- a ncl bla'nkfiri iinterme shijngrelation" I ete theelitten nd blank in mi imaginary -=urv'i linear rack conjugate tq boththeentten and ating teeth in a gea bl'ank with alg cutter having helical "teeth? hiehfeoinpri a .efiectin'gf an vsinte'rineshing 'iielatiohshipf be' s tween theblank andxthe 'cutteii aiiclfaii', narycnrVil-inear rack cenjiigat' t0 libthypbsi tiOning 'the cutter v ith its axi's'f at eagle ship; I relatively reciprocating the cutteif; and blank acress-tlieinfaees infthe directi'en 'ofith axisibfithejblank; andlfeeding the' ciittery laterally-with nespebtt0 theaxi's df tiie blank While maintaining intern 'eshing relationship between the mitten-the blank and the nary 'curvilinjafiac'k.

comprises pesitioningthe' Cutter fwith itsiaxi s' at an'angle to the axisof the "'b-lankvce rr'e -i spending tethe'helix' angle otthteth-of cutter, i'elativ 1y" blank, retatin the'icnttei and blankat the by -an imagi-naryeurvilineai' rack moving along-said tangent-line, 'aiidient ve1y eei 5 roeating the' 'cuttef and' "blank transversely 'of theface of the latter tof"genei"'ateQth teeth; 109' 'O'fthe gear blank; 1 E -if '4 "i f =3 e 18'. The hereinclescribed method of gene'rg ating helical teeth ofone handinage'ar blank .g,

with, a gear shap er cutter ofth "opposite handfwhich mp 'ises'posl angle te each other corresponding :to

feience between the 'helix' anglef'of the 'utt'e'i f] I generated in the blank, spelatii 'ely'motzin the -1- -cntjter;and blank laterally along ia'ebin curvilinear 'line tangent te the; pitch fbireles (if the cutter; and blank,"*retating 'thi Clitten and blank at therates; atwhich they'a ivbUildf be riv k y al'fl imagina r "-clii vil'ineai'flraek moving along saidftange hie,andfrelat iiiei 1y ireciproca-tiiigtheeutte and b1 nk the gear'blaiiki In t stimony wherebiiaifiiiimy slgna tn re 17.;The herein de's'cifi hed'methbd 0f genei'k ating'straightiteeth i i a gear blank with'ia,

gear shaper'c'ut't'er having helical teeth Whili i .3 i v ovin fthe,cntterand blan'k "laterally alejngwa conimon:curvi1i earline tangent te' 'the' pitehii'cles oft-he ciltteif'and 'tieningthe axesvof thefcnttenand blank at 1 

